Regulator key

Abstract

A regulator key whose arms ensure clearance of a balance spring even in event of shocks.

The invention claimed is: 
     
       1. A regulator key for a timepiece movement comprising:
 a base configured to be attached to a regulator and carrying two arms configured to limit clearance of a balance spring, 
 wherein the two arms project from the base parallel to each other, leaving an interstice configured to receive the balance spring, 
 wherein the two arms each include a projecting surface which decreases in width along a length of the arm away from the base to limit dimensions of an end of the regulator key and the two arms each include a partially hollow central portion so that a free end of each arm forms a hook extending mainly parallel to the longitudinal direction of the interstice and running alongside the interstice configured to receive the balance spring, and 
 wherein a portion of the projecting surface which decreases away from the base is located at a same position along a longitudinal axis of the regulator key as the partially hollow central portions. 
 
     
     
       2. A regulator key according to  claim 1 , wherein the two hooks extend in opposite directions. 
     
     
       3. A regulator key according to  claim 1 , wherein the regulator key has an axis of symmetry passing through the center of the base. 
     
     
       4. A regulator key according to  claim 1 , wherein the sides of the two arms running alongside the interstice are substantially C-shaped. 
     
     
       5. A regulator key according to  claim 1 , wherein the sides of the two arms running alongside the interstice are flat. 
     
     
       6. A regulator key according to  claim 1 , wherein the sides of the two arms running alongside the interstice are parallel. 
     
     
       7. A regulator key according to  claim 1 , wherein surfaces of the sides of the two arms running alongside the interstice, which face each other, are substantially I-shaped. 
     
     
       8. A timepiece movement comprising:
 a resonator including a balance and balance spring; and 
 a regulator system adjusting an active length of the balance spring; 
 wherein the regulator system includes a regulator key including a base configured to be attached to a regulator and carrying two arms configured to limit clearance of a balance spring, wherein the two arms project from the base parallel to each other, leaving an interstice configured to receive the balance spring; 
 wherein the two arms each include a projecting surface which decreases in width along a length of the arm away from the base to limit dimensions of an end of the regulator key and the two arms each include a partially hollow central portion so that a free end of each arm firms a hook extending mainly parallel to the longitudinal direction of the interstice and running alongside the interstice configured to receive the balance spring, and 
 wherein a portion of the projecting surface which decreases away from the base is located at a same position along a longitudinal axis of the regulator key as the partially hollow central portions.